Fait mathématique: 2557 is the number of proper divisors of the 15^{th} perfect number.
Culture générale: 2557 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: December 31st is the day in 1907 that the first New Year's Eve celebration is held in Times Square (then known as Longacre Square) in New York, New York.